The present invention relates to circuitry for applying the output of a DC electrical power source, having its output presented by more than two electrodes, into a two-terminal load resistance with a minimum of power lost in the circuit components. The circuitry of the present invention may find particular utility for connecting a multi-terminal magnetohydrodynamic (MHD) generator or other power source that provides dc or pulsating dc current of pulse duration from a few tenths of a second to continuous dc.
In MHD generators of the multi-electrode type in which the load current is extracted from the generator through more than one pair of electrodes, a common problem is encountered in dividing the current more or less equally among the electrodes at the positive side of the generator, and likewise in dividing the load current equally among the electrodes at the negative side of the generator. This is done to prevent overheating of any one electrode, since the current will not normally divide evenly unless constrained to do so. With existing MHD power systems, a resistor is used at each electrode of suitable resistance to force the equal distribution of current; the result is a complex load circuit which generally dissipates about 15 to 20 percent of the MHD output power in the current dividing resistors. All the power of the MHD generator is therefore not available for use into a single two terminal load.
The present invention comprises a tapped output transformer in conjunction with novel converter circuitry which permits substantially all the output power of a DC power source having multiple output electrode pairs, to be delivered to a two-terminal load, while dividing the output current among the electrodes of the generator according to a predetermined current distribution scheme. The invention saves the power normally lost in ballast resistors connected to MHD generators that have a two-terminal load and more than one pair of output electrodes. Since the segmented electrode MHD generator in many applications has the greatest efficiency among the various open cycle combustion MHD generator styles, efficiently directing the current from such a generator into a two-terminal load is an important problem in the art which is solved by the present invention.
It is, therefore, a principal object of the present invention to provide an improved current distribution circuit for MHD generator electrodes.
It is a further object of the invention to provide a load circuit for a DC power source that delivers its output current through more than one pair of output electrodes, each electrode to carry a specified fraction of the total load current.
It is a further object of the invention to provide a circuit for controlling the current at the output of MHD generators, which circuit divides the current among the various output electrodes in predetermined fashion, while permitting essentially all of the output power to be utilized into a two-terminal load.
It is a further object of the invention to provide a nondissipative current distribution circuit for an MHD generator or like power generator operating into a resonant converter circuit, or nonresonant converter circuit with power transformer.
These and other objects of the present invention will become apparent as the detailed description of certain representative embodiments thereof proceeds.